JPH0754953A - Fixture of ball screw controlling sealed rack in freezing drying tank - Google Patents

Abstract

PURPOSE: To easily replace a nut, suppress abrasion, and also facilitate assembly and disassembly by engaging the lower extremity of a ballscrew in a nut with a nil pitch and cooperating the horizontal groove of the nut with the semicylindrical groove of the ballscrew. CONSTITUTION: In the inside of a freeze-drying tank, a ballscrew 4 is attached which controls a pin supporting rack 2 supported on the bottom part of the tank. At this time, the lower extremity of the ballscrew 4 is engaged in a nut 6 with a nil pitch. Respective horizontal and parallel grooves 7 for receiving balls 8 are arranged in the nut 6. The respective horizontal grooves 7 are made to cooperate with respective semicylindrical grooves 9 arranged in the ballscrew 4. At least one of imperviousness systems 19, 20 is mounted on both sides of the nut 6 for preventing the penetration of foreign matters between the ballscrew 4 and the nut 6. Thereby, the nut 6 can be easily replaced and also can act as a stepped bearing, and abrasion can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a freeze-drying tank, and more particularly to a special mounting of a ball screw for controlling a sealed rack arranged in the tank.

[0002]

2. Description of the Related Art In order to prevent the freeze-dried product in a tank from coming into contact with the outside air, it is necessary to seal the bottle containing the product even in the freeze-drying chamber. One desirable technique therefor is to distribute the bins over stacked racks and arrange them such that they are supported above the bins supported by the racks directly below, with all racks stacked. Also, drive each rack into a stopper until all bins are stopped. To prevent the control jack rods from entering the tank and dust or non-sterile products from entering the tank, a mechanism controlling these racks can be used to prevent the risk of contamination. Applicant's document FR-A2,655,020
At least one of the racks is suspended from a horizontally disposed sealing girder at the top of the tank in a bottle sealing mechanism distributed over a rack of a refrigeration tank, said girder extending vertically into the tank. The present invention relates to a mechanism that can be moved from the bottom to the top inside the tank and from the top to the bottom by two ball screws. A single external motor drives the screw in rotation, and the impermeability of the tank is conveniently carried out by the sleeve holding the fitting.

The ball screws carrying the weight of the hermetically sealed girders, racks and those mounted on them must be very precisely located and fixedly supported on the bottom of the tank. Therefore, generally, a stainless steel ring is fixed to the lower end of each screw, and these rings are
It abuts bearings carried by at least two metal supports fixed to the bottom of the tank and fixed to the ring. These bearings are preferably coated with a ceramic powder loaded with Teflon so that the ring, which rotates with the screw, slides on the fixed bearings with as little friction as possible.

[0004]

The ring, like the bearing, is moved to support extremely high stresses, and care must be taken to ensure complete alignment of the screws in the bearing, but with friction with the stainless steel ring. The parts become worn and these rings and parts cannot withstand high pressure. In addition, this type of ring support is sensitive to debris and contaminants slipping between the rings, causing rapid deterioration of the ring with stress concentration due to slight plastic deformation of the tank during temperature / pressure cycling. Occurs.

[0005]

[Means for Solving the Problems] As a result of such an abnormality,
Applicants have found a system that solves these problems but facilitates assembly, disassembly and maintenance.

Accordingly, a primary object of the present invention is to provide a ball screw mounting device for controlling a bin support rack supported at the bottom of a tank in a freeze-drying tank, with the lower end of each screw engaged in a zero pitch nut. ,
Each of the nuts comprises horizontal grooves parallel to each other for receiving a ball, the grooves cooperating with grooves provided on the screw, and the foreign matter is prevented from entering between the screw and the nut. It is an object of the present invention to provide a ball screw mounting device for controlling a sealed rack of a freeze-drying tank which is provided with at least one impervious system on both sides of the nut.

According to an embodiment of the invention, the lower end of the screw carries a sleeve provided with the groove and the nut is mounted on a bracket fixed to the bottom of the tank in two hemispheres. It is housed inside a shaped cage. In addition, the nut is provided with an opening for placing the ball in the corresponding groove.

According to another embodiment of the invention, the impervious system comprises sintered stainless steel rings mounted on the upper and lower parts of the sleeve, the rings being formed of a flexible synthetic material. Supported by joints.

The present invention will now be described in detail with reference to the embodiments shown in the drawings, but the present invention is not limited thereto.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The apparatus shown in FIG. 1 is mounted in a freeze-drying tank 1, which contains a plurality of racks 2, which are mounted on at least two ball screws 4 via nuts 5. It is driven by the sealed girder 3 supported by the. The screws 4 extend vertically on both the upper and lower sides of the rack over the entire length of the tank. FIG. 2 shows in detail the lower end of each screw 4 engaged in the nut 6 with zero pitch.
That is, the nut 6 comprises horizontal grooves 7 parallel to one another for receiving several balls 8, which balls 8 are housed in corresponding semi-cylindrical grooves 9 also provided in the end sleeve 10 of said screw. To be done. The outer shape of the nut 6 is spherical and acts as a pot-type joint so as to ensure the optimum operating conditions of the roller bearing without parasitic stress, and the nut has two hemispherical shapes mounted on a bracket. It is housed in a cage (11, 12) and the whole unit is fixed by screws 14 to the bottom of the tank. The sleeve 10 is screwed by a key 15
Fixed against. The pin 16 then forms the link between the nut 6 and the cage (11, 12). A plurality of openings 17 (only one of which is shown) are provided in the nut 6 for placing the balls 8 in the corresponding grooves 7. A lock bolt 18 is provided at the lower ends of the screw 4 and the sleeve 10. Sintered stainless steel rings 19 are attached to the upper and lower ends of the sleeve 10 so as to prevent foreign matter from entering the annular space between the nut 6 and the sleeve 10, and these rings are attached to the sleeve 10. On the other hand, it is held by a molded joint of flexible synthetic material. These rings 19 are used to filter dust and debris, but allow water vapor and gases to pass through, thus degassing the structure. Lower filter 1
9 is arranged so that it does not cause an accumulation of condensed water, which is naturally evaporated during the steam sterilization stage.

The top of each ball screw at the level of the sealing girder is shown in detail in FIG. A nut 5 tightens the ball screw 4 as shown in this figure. Nut 5
Is connected to the girder body 3 by a key system 22. It can be seen that there is a space 23 between the nut 5 and the girder body 3, and this space 23 forms a clearance between the screw 4 and the girder 3. This play provides a certain degree of freedom of movement of the movable nut 5 with respect to the sealed girder 3 and absorbs the differential expansion between the girder 3 and the rest of the tank. Also as can be seen from this figure, the sealing girders 3 can cooperate with the ball screws 4 on both sides of the nut 5 via sintered stainless steel rings 19 supported by molded joints 21. This joint 21 has a shape corresponding to the spiral groove of the screw 4, and can prevent foreign matter from entering despite the relative movement of each element.

[0012]

As described above, the zero pitch nut 6 can be easily replaced. Depending on the size of the tank and the load carried by the screw, the nut 6 comprises a certain number of grooves accommodating a plurality of balls. The nut 6 acts as a step bearing and is less likely to wear due to the impervious means provided therein.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a freeze-drying tank.

FIG. 2 is an enlarged sectional view showing a mounting structure of a lower portion of a ball screw.

FIG. 3 is an enlarged sectional view of the nut of the hermetically sealed girder.

[Explanation of symbols]

 1 Tank 2 Rack 3 Girder 4 Ball Screw 5 Nut 6 Nut 7 Groove 9 Groove 8 Ball 10 Sleeve 11 Cage 12 Cage 13 Bracket 15 Key 16 Connecting Pin 17 Opening 19 Stainless Steel Ring 20 Molded Joint 21 Molded Joint 22 Key 23 Space

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F26B 5/06 9140-3L 25/06 Z 9140-3L

Claims (9)

[Claims] 1. A device for mounting a ball screw for controlling a bin support rack supported at the bottom of a tank in a freeze-drying tank, wherein the lower end of each screw (4) is engaged in a zero pitch nut (6). , Said nut comprises mutually parallel horizontal grooves (7) for receiving respective balls (8), said grooves (7) being screws (4)
At least one impervious system on each side of the nut (6) to cooperate with a groove (9) provided in the same and to prevent foreign matter from entering between the screw (4) and the nut (6). (19, 20) is provided, The mounting device of the ball screw which controls the sealed rack in a freeze-drying tank characterized by the above-mentioned. 2. Ball screw mounting device according to claim 1, characterized in that the lower end of the screw (4) carries a sleeve (10) with the groove (9). 3. The nut (6) is housed inside two hemispherical cages (11, 12) mounted on a bracket (13) fixed to the bottom of the tank. Item 1. A ball screw attaching device according to item 1. 4. Ball screw mounting device according to claim 2, characterized in that the sleeve (10) is connected to the screw (4) by means of a key (15). 5. Ball screw mounting device according to claim 3, characterized in that a pin (16) ensures a connection between the nut (6) and the cage (11, 12). 6. Ball screw mounting device according to claim 1, characterized in that the nut (6) is provided with an opening (17) for placing the ball in a corresponding groove (7). 7. The impervious system comprises the sleeve (1).
0) consisting of sintered stainless steel rings (19) mounted on the top and the bottom, these rings being supported by molded joints (20) of flexible synthetic material. The ball screw attaching device according to any one of 1 and 2. 8. Ball screw mounting according to claim 1 or 7, characterized in that the impervious system (19) is mounted on the upper and lower sides of the nut (5) of the sealing girder (3). apparatus. 9. A certain clearance is provided between the nut (5) and the sealing girder (3) so as to absorb the differential expansion between the girder (3) and the rest of the tank. 9. Ball screw mounting device according to claim 8, characterized in that it has a certain degree of freedom of movement and that the joint (21) has a shape corresponding to the spiral groove of the screw (4).